{"api_version":"1","generated_at":"2026-05-13T07:47:46+00:00","cve":"CVE-2024-26923","urls":{"html":"https://cve.report/CVE-2024-26923","api":"https://cve.report/api/cve/CVE-2024-26923.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2024-26923","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2024-26923"},"summary":{"title":"af_unix: Fix garbage collector racing against connect()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Fix garbage collector racing against connect()\n\nGarbage collector does not take into account the risk of embryo getting\nenqueued during the garbage collection. If such embryo has a peer that\ncarries SCM_RIGHTS, two consecutive passes of scan_children() may see a\ndifferent set of children. Leading to an incorrectly elevated inflight\ncount, and then a dangling pointer within the gc_inflight_list.\n\nsockets are AF_UNIX/SOCK_STREAM\nS is an unconnected socket\nL is a listening in-flight socket bound to addr, not in fdtable\nV's fd will be passed via sendmsg(), gets inflight count bumped\n\nconnect(S, addr)\tsendmsg(S, [V]); close(V)\t__unix_gc()\n----------------\t-------------------------\t-----------\n\nNS = unix_create1()\nskb1 = sock_wmalloc(NS)\nL = unix_find_other(addr)\nunix_state_lock(L)\nunix_peer(S) = NS\n\t\t\t// V count=1 inflight=0\n\n \t\t\tNS = unix_peer(S)\n \t\t\tskb2 = sock_alloc()\n\t\t\tskb_queue_tail(NS, skb2[V])\n\n\t\t\t// V became in-flight\n\t\t\t// V count=2 inflight=1\n\n\t\t\tclose(V)\n\n\t\t\t// V count=1 inflight=1\n\t\t\t// GC candidate condition met\n\n\t\t\t\t\t\tfor u in gc_inflight_list:\n\t\t\t\t\t\t  if (total_refs == inflight_refs)\n\t\t\t\t\t\t    add u to gc_candidates\n\n\t\t\t\t\t\t// gc_candidates={L, V}\n\n\t\t\t\t\t\tfor u in gc_candidates:\n\t\t\t\t\t\t  scan_children(u, dec_inflight)\n\n\t\t\t\t\t\t// embryo (skb1) was not\n\t\t\t\t\t\t// reachable from L yet, so V's\n\t\t\t\t\t\t// inflight remains unchanged\n__skb_queue_tail(L, skb1)\nunix_state_unlock(L)\n\t\t\t\t\t\tfor u in gc_candidates:\n\t\t\t\t\t\t  if (u.inflight)\n\t\t\t\t\t\t    scan_children(u, inc_inflight_move_tail)\n\n\t\t\t\t\t\t// V count=1 inflight=2 (!)\n\nIf there is a GC-candidate listening socket, lock/unlock its state. This\nmakes GC wait until the end of any ongoing connect() to that socket. After\nflipping the lock, a possibly SCM-laden embryo is already enqueued. And if\nthere is another embryo coming, it can not possibly carry SCM_RIGHTS. At\nthis point, unix_inflight() can not happen because unix_gc_lock is already\ntaken. Inflight graph remains unaffected.","state":"PUBLISHED","assigner":"Linux","published_at":"2024-04-25 06:15:57","updated_at":"2026-05-12 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the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Fix garbage collector racing against connect()\n\nGarbage collector does not take into account the risk of embryo getting\nenqueued during the garbage collection. If such embryo has a peer that\ncarries SCM_RIGHTS, two consecutive passes of scan_children() may see a\ndifferent set of children. Leading to an incorrectly elevated inflight\ncount, and then a dangling pointer within the gc_inflight_list.\n\nsockets are AF_UNIX/SOCK_STREAM\nS is an unconnected socket\nL is a listening in-flight socket bound to addr, not in fdtable\nV's fd will be passed via sendmsg(), gets inflight count bumped\n\nconnect(S, addr)\tsendmsg(S, [V]); close(V)\t__unix_gc()\n----------------\t-------------------------\t-----------\n\nNS = unix_create1()\nskb1 = sock_wmalloc(NS)\nL = unix_find_other(addr)\nunix_state_lock(L)\nunix_peer(S) = NS\n\t\t\t// V count=1 inflight=0\n\n \t\t\tNS = unix_peer(S)\n \t\t\tskb2 = sock_alloc()\n\t\t\tskb_queue_tail(NS, skb2[V])\n\n\t\t\t// V became in-flight\n\t\t\t// V count=2 inflight=1\n\n\t\t\tclose(V)\n\n\t\t\t// V count=1 inflight=1\n\t\t\t// GC candidate condition met\n\n\t\t\t\t\t\tfor u in gc_inflight_list:\n\t\t\t\t\t\t  if (total_refs == inflight_refs)\n\t\t\t\t\t\t    add u to gc_candidates\n\n\t\t\t\t\t\t// gc_candidates={L, V}\n\n\t\t\t\t\t\tfor u in gc_candidates:\n\t\t\t\t\t\t  scan_children(u, dec_inflight)\n\n\t\t\t\t\t\t// embryo (skb1) was not\n\t\t\t\t\t\t// reachable from L yet, so V's\n\t\t\t\t\t\t// inflight remains unchanged\n__skb_queue_tail(L, skb1)\nunix_state_unlock(L)\n\t\t\t\t\t\tfor u in gc_candidates:\n\t\t\t\t\t\t  if (u.inflight)\n\t\t\t\t\t\t    scan_children(u, inc_inflight_move_tail)\n\n\t\t\t\t\t\t// V count=1 inflight=2 (!)\n\nIf there is a GC-candidate listening socket, lock/unlock its state. This\nmakes GC wait until the end of any ongoing connect() to that socket. After\nflipping the lock, a possibly SCM-laden embryo is already enqueued. And if\nthere is another embryo coming, it can not possibly carry SCM_RIGHTS. At\nthis point, unix_inflight() can not happen because unix_gc_lock is already\ntaken. Inflight graph remains unaffected."}],"providerMetadata":{"dateUpdated":"2026-05-11T20:06:59.719Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a36ae0ec2353015f0f6762e59f4c2dbc0c906423"},{"url":"https://git.kernel.org/stable/c/343c5372d5e17b306db5f8f3c895539b06e3177f"},{"url":"https://git.kernel.org/stable/c/2e2a03787f4f0abc0072350654ab0ef3324d9db3"},{"url":"https://git.kernel.org/stable/c/e76c2678228f6aec74b305ae30c9374cc2f28a51"},{"url":"https://git.kernel.org/stable/c/b75722be422c276b699200de90527d01c602ea7c"},{"url":"https://git.kernel.org/stable/c/507cc232ffe53a352847893f8177d276c3b532a9"},{"url":"https://git.kernel.org/stable/c/dbdf7bec5c920200077d693193f989cb1513f009"},{"url":"https://git.kernel.org/stable/c/47d8ac011fe1c9251070e1bd64cb10b48193ec51"}],"title":"af_unix: Fix garbage collector racing against connect()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2024-26923","datePublished":"2024-04-24T21:49:22.001Z","dateReserved":"2024-02-19T14:20:24.194Z","dateUpdated":"2026-05-12T11:50:40.454Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2024-04-25 06:15:57","lastModifiedDate":"2026-05-12 12:16:26","problem_types":["CWE-362"],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":4.7,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1,"impactScore":3.6}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.23","versionEndExcluding":"4.19.314","matchCriteriaId":"2331DB2D-5410-4229-9EDF-C756966401BB"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"5.4.275","matchCriteriaId":"5FF6D8DE-C559-4586-86C8-2C6B4420A2C2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"5.10.216","matchCriteriaId":"A44ABF89-F1BD-4C9A-895D-7596650DCD27"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"5.15.156","matchCriteriaId":"E80AFAB4-A9F3-415C-8D6C-52D1C13F1531"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.1.87","matchCriteriaId":"BDA59296-EDB8-44CD-98E4-C08C051569E6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.6.28","matchCriteriaId":"8D6315B0-B3BA-406C-B0DB-51D9A63753F0"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.8.7","matchCriteriaId":"531BDFB5-EF6A-4707-902E-146368303499"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.9:rc1:*:*:*:*:*:*","matchCriteriaId":"22BEDD49-2C6D-402D-9DBF-6646F6ECD10B"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.9:rc2:*:*:*:*:*:*","matchCriteriaId":"DF73CB2A-DFFD-46FB-9BFE-AA394F27EA37"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.9:rc3:*:*:*:*:*:*","matchCriteriaId":"52048DDA-FC5A-4363-95A0-A6357B4D7F8C"}]}]},{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*","matchCriteriaId":"07B237A9-69A3-4A9C-9DA0-4E06BD37AE73"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2024","CveId":"26923","Ordinal":"1","Title":"af_unix: Fix garbage collector racing against connect()","CVE":"CVE-2024-26923","Year":"2024"},"notes":[{"CveYear":"2024","CveId":"26923","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Fix garbage collector racing against connect()\n\nGarbage collector does not take into account the risk of embryo getting\nenqueued during the garbage collection. If such embryo has a peer that\ncarries SCM_RIGHTS, two consecutive passes of scan_children() may see a\ndifferent set of children. Leading to an incorrectly elevated inflight\ncount, and then a dangling pointer within the gc_inflight_list.\n\nsockets are AF_UNIX/SOCK_STREAM\nS is an unconnected socket\nL is a listening in-flight socket bound to addr, not in fdtable\nV's fd will be passed via sendmsg(), gets inflight count bumped\n\nconnect(S, addr)\tsendmsg(S, [V]); close(V)\t__unix_gc()\n----------------\t-------------------------\t-----------\n\nNS = unix_create1()\nskb1 = sock_wmalloc(NS)\nL = unix_find_other(addr)\nunix_state_lock(L)\nunix_peer(S) = NS\n\t\t\t// V count=1 inflight=0\n\n \t\t\tNS = unix_peer(S)\n \t\t\tskb2 = sock_alloc()\n\t\t\tskb_queue_tail(NS, skb2[V])\n\n\t\t\t// V became in-flight\n\t\t\t// V count=2 inflight=1\n\n\t\t\tclose(V)\n\n\t\t\t// V count=1 inflight=1\n\t\t\t// GC candidate condition met\n\n\t\t\t\t\t\tfor u in gc_inflight_list:\n\t\t\t\t\t\t  if (total_refs == inflight_refs)\n\t\t\t\t\t\t    add u to gc_candidates\n\n\t\t\t\t\t\t// gc_candidates={L, V}\n\n\t\t\t\t\t\tfor u in gc_candidates:\n\t\t\t\t\t\t  scan_children(u, dec_inflight)\n\n\t\t\t\t\t\t// embryo (skb1) was not\n\t\t\t\t\t\t// reachable from L yet, so V's\n\t\t\t\t\t\t// inflight remains unchanged\n__skb_queue_tail(L, skb1)\nunix_state_unlock(L)\n\t\t\t\t\t\tfor u in gc_candidates:\n\t\t\t\t\t\t  if (u.inflight)\n\t\t\t\t\t\t    scan_children(u, inc_inflight_move_tail)\n\n\t\t\t\t\t\t// V count=1 inflight=2 (!)\n\nIf there is a GC-candidate listening socket, lock/unlock its state. This\nmakes GC wait until the end of any ongoing connect() to that socket. After\nflipping the lock, a possibly SCM-laden embryo is already enqueued. And if\nthere is another embryo coming, it can not possibly carry SCM_RIGHTS. At\nthis point, unix_inflight() can not happen because unix_gc_lock is already\ntaken. Inflight graph remains unaffected.","Type":"Description","Title":"af_unix: Fix garbage collector racing against connect()"}]}}}